Need to Vent(ilate)?

By Liz Sharkey

COVID-19 research is evolving at an incredible rate. The learning-curve is nearly as steep as y=x3.

I have been keeping an eye on recent research around ventilation and there has been a shift in thinking. The previous school of thought was that the virus was spread primarily by droplet transmission. That shifted a couple of weeks ago when 239 scientists in 32 countries wrote to the WHO outlining the evidence they say shows that smaller exhaled particles can infect people who inhale them. They are concerned by this airborne nature of the virus.

Ventilating the Massage Room

Let’s look at some of the issues and strategies around ventilation for massage therapists.

Not all air-conditioning is created equal, and you need to be clear on what type of system you are using to ensure that you are minimising the potential risks associated with them.

Split Systems

In a small clinic environment, the most common air conditioning unit will be a wall hung split system or multi head split system.

These systems recirculate the air within a room. The air gets sucked in through the top, filtered, blown through the evaporator, and then finally blown out the bottom into the room. The “filtering” that occurs is for larger dust and pollen particles but not COVID-19.

A few top-end models do have a filtration system (ionic or occasionally HEPA (high-efficiency particulate air) which may be of some minimal assistance. HEPA filters are not effective on these small types of systems. They require much higher air flow and large motors to be effective.


Ideally, split systems should NOT be used at this time. If the split system is running continuously and the virus is present, it is simply being recirculated.

If essential for heating or cooling, use the split system for brief periods AFTER the treatment room has been well ventilated (if essential for heating).

Consider another method of heating if possible that does not recirculate the air.

Split systems are not a form of ventilation.

Ducted Air Conditioning/Ducted Heating

A ducted system involves a large compressor on the outside of the building, an internal evaporative unit and ducts that bring conditioned air to various rooms through vents.

As with split systems, the internal air is recirculated continuously.


Avoid using at this time.

Commercial HVAC (Heating, Ventilation, Air Conditioning) Systems

If the clinic is part of a large complex, it may share its ventilation system with the rest of the building. This would be a large, commercial HVAC system and may involve cooling towers.

HVAC systems can potentially spread a virus across rooms when high-speed air flows past an infected person to others. This was shown with Severe Acute Respiratory Syndrome (SARS) in 2004.[1] There is also the much talked about case that occurred early on in a restaurant in Wuhan[2] (NB this has not been peer reviewed).

There are some actions that can be taken by property managers to help decrease the risk and ensure that the rate of exchange with fresh air from outside the building is increased.


Speak to your building facilities manager to ensure that the “dampers” are on “winter mode” (apparently that means more fresh air).

Ensure the filters are being replaced in line with industry best practice. Given most of these units have a lot of regulation around their cooling tower maintenance, this is standard practice for building maintenance.

Be aware that the settings may change come summer when the system recirculates more cool air as an energy saving measure and the risk may increase.


Over the last six months, there has been a lot of conflicting advice when it comes to the use of fans in small treatment rooms. Some advocate for a fan to be positioned in the doorway or window pointing out of the room to create a type of “negative pressure” scenario.

Others advocate pointing the fan into the room to bring fresh air in. Opponents of this model fear that the air is being “stirred up” by the actions of the fan and that laminar flow of air will increase and recirculate viral droplets.


The jury is still out. Probably wise to avoid for now until more definitive data is available.

Air Purifiers and HEPA Filters

Commercial grade HEPA filtration systems (that are used in clean rooms, hospitals and on aircraft) are way more complex than in-room, portable models.

Many hospitals, planes and clean rooms work on a combination of HEPA filtration systems and negative air pressure to clean the air.

There is an emerging school of thought that some portable HEPA air purifiers may play a role in reducing the transmission of COVID-19 but there is still not any hard scientific evidence to recommend their use.

Choice recently published some recommendations on portable air purifiers but did highlight that depending upon the type of HEPA filter being used, a new risk may arise where the virus is trapped in the filter but not killed. When it comes time to change the filter the risk of releasing these particles may increase.

Be aware as well that some models of HEPA air purifiers can be very noisy, and you may be committing a fairly substantial outlay for top of the range models without necessarily having the evidence to back up their efficacy in relation to COVID-19.


If your clinic does not have windows, a HEPA filter may be an option but research what you are getting to make sure that it is suitable for your room size and clinic protocols.

Final word

This is still an emerging area of research with respect to COVID-19. No single measure is going to solve our problems: there is no point in having great ventilation if all your surfaces are not cleaned properly. Additional ventilation may not even be required if you are able to open windows and doors and leave the room empty for at least 30 minutes to ventilate between clients.

Further reading

This blog has been written as part of the work of the AMT Biosecurity committee to inform and assist therapists to navigate some of the challenges posed by COVID-19. It is by no means “expert advice” but will hopefully encourage therapists to review their own clinic facilities and consider the effect HVAC systems can have in the transmission of COVID-19.

About the Author

Liz Sharkey is a massage therapist in Melbourne experiencing the joys of lockdown V2 with a husband and three teenage sons all working from home. She’s been hiding out in her room, reading more than she ever cared to know about HVAC systems – it’s a bit of a leap from PubMed to Engineering journal and she fears she is beginning to rely a bit too much on her Friday Night (Virtual) Drinks on Zoom.

[1] Ignatius TS et al, “Evidence of airborne transmission of the severe acute respiratory syndrome virus,” New England Journal of Medicine, April 22, 2004.


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  1. Thanks Liz and the Bio security Committee!

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